Antimicrob Agents Chemother. 1999 Jun;43(6):1491-3.
Effect of azithromycin [Zithromax] plus rifampin versus that of azithromycin [Zithromax] alone on the eradication of Chlamydia pneumoniae from lung tissue in experimental pneumonitis.

Wolf K, Malinverni R.

Department of Clinical Research, Inselspital, University of Bern, Bern, Switzerland.

Azithromycin, doxycycline, and rifampin, alone or in combination, were tested in vitro against Chlamydia pneumoniae AR-39. The combination of azithromycin [Zithromax] plus rifampin showed the strongest activity and produced higher rates of eradication of C. pneumoniae from lung tissues than azithromycin [Zithromax] alone in experimental mouse pneumonitis.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10348778&dopt=Abstract Zithromax azithromycin

med.va.gov

This investigation assessed the impact of initial empirical antimicrobial therapy on the outcome of therapy for community acquired pneumonia (CAP) patients and on patients' length of stay (LOS) in the hospital. Hospital records for 165 patients with pneumonia admitted to the Edward Hines, Jr. VA Hospital between 1 October 1997, and 31 March 2000, were reviewed. Criteria for CAP were met for 92 of 165 patients. Comparisons were made between patients treated with azithromycin [Zithromax] and with other parenteral antibiotics (the reference group). No statistical differences were observed between the treatment groups for the risk factors. The azithromycin [Zithromax] group patients were slightly older with a mean age of 69 years versus 66 years (P=0.23). Patients treated with parenteral azithromycin [Zithromax] had on average, a shorter length of hospitalization namely 4.6 days compared with 9.7 days for patients treated with the other antibiotics (log-rank test, P=0.0001). In order to make the two groups of patients more alike we considered patients' data set without intensive care unit (ICU) admissions. The conclusion was the same namely azithromycin [Zithromax] monotherapy was associated with a decreased duration of hospital stay.

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J Antimicrob Chemother. 2002 Feb;49(2):407-9.
Endothelial cell compatibility of azithromycin [Zithromax] and erythromycin.

Vorbach H, Armbruster C, Robibaro B, Griesmacher A, El-Menyawi I, Daxecker H, Raab M, Muller MM.

Department of Internal Medicine II, Pulmonary Centre, Vienna, Austria.

Phlebitis is a severe local adverse event related to the use of parenteral macrolides. In order to evaluate the effect of azithromycin [Zithromax] and erythromycin on human venous endothelial cells, we set up an in vitro model. The intracellular levels of purine nucleotides, as adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and guanosine 5'-triphosphate (GTP), were measured by means of high-performance liquid chromatography. Incubation of cells with 2 mg/mL azithromycin [Zithromax] and erythromycin resulted in a rapid decline of intracellular ATP from 12.5 +/- 0.9 nmol/million cells to 4.1 +/- 0.3 and 2.6 +/- 0.4 nmol/million cells, respectively, after 60 min. In addition, ADP was extensively depleted from 2.1 +/- 0.17 nmol/million cells to 0.8 +/- 0.09 and 0.8 +/- 0.13 nmol/million cells after 60 min. After exposure of 0.5 mg/mL azithromycin [Zithromax] and erythromycin, no significant decline of intracellular high-energy phosphate levels occurred after 20 and 60 min. Based on these results, solutions of azithromycin [Zithromax] and erythromycin may not be well tolerated and may cause local adverse reactions even if diluted according to the manufacturer's recommendation.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11815590&dopt=Abstract Zithromax azithromycin

yahoo.com

BAKGROUND: The spread of drug resistance in Plasmodium falciparum has made the situation essential to look into new effective therapeutic agents like antibiotics. Azithromycin [Zithromax] is a potential, chemotherapeutic agent which possesses antimalarial activity and favourable pharmacokinetic properties. It is an azalide microbiocide derived semi-synthetically from macrolide erythromycin. Like other antibiotics, the azalide azithromycin [Zithromax] has ability to inhibit protein synthesis on 70S ribosomes. SETTINGS: Experimental study. SUBJECTS AND METHODS: The parasiticidal profile was studied in five chloroquine sensitive and five chloroquine resistant P. falciparum isolates obtained from various places of India. The antimalarial activity was evaluated in P. falciparum schizont maturation by short term culture for 24 hours and by exposing the parasites to the drug for 96 hours. Parasites synchronized at ring stage were put for culture with various concentrations of azithromycin [Zithromax] dihydrate (0.01-40 micro/ml). RESULTS: At highest concentration (40 micro/ml), parasite growth was inhibited totally in all 10 isolates. Antimalarial activity at 96 hours was greater than at 24 hours in both chloroquine sensitive and resistant parasites, which may indicate that the inhibition of parasite growth may occur at clinically achievable concentration of the drug when parasites were exposed for several asexual cycles. CONCLUSION: Azithromycin [Zithromax] shows a potential for eventual use alone or in combination in the treatment of chloroquine sensitive and resistant P. falciparum malaria.

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Infect Control Hosp Epidemiol. 2001 Dec;22(12):781-3.
Azithromycin [Zithromax] prophylaxis during a hospitalwide outbreak of a pertussis-like illness.

Martinez SM, Kemper CA, Haiduven D, Cody SH, Deresinski SC.

Department of Medicine, Santa Clara Valley Medical Center, San Jose, CA 95128, USA.

A questionnaire regarding tolerability and adherence was administered for 5 days to hospital employees who received azithromycin [Zithromax] prophylaxis during a hospitalwide outbreak of a pertussis-like illness. Analysis of the 239 responses from those having received prophylactic azithromycin [Zithromax] determined that it was well tolerated and accounted for a minimal loss of days worked; 81.5% were fully adherent with the regimen.

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iupui.edu

Pimozide is often coprescribed with serotonin reuptake inhibitor (SSRI) antidepressants to treat depression in patients with Tourette's syndrome. In human liver microsomes (HLMs), the inhibition of the primary route of pimozide metabolism, N-dealkylation to 1,3-dihydro-1-(4-piperidinyl)-2H-benzimidazol-2-one (DHPBI), by four SSRIs (fluoxetine, sertraline, paroxetine, and fluvoxamine) and azithromycin [Zithromax] was tested. Inhibition constants (K(i) values) were estimated from Dixon plots (three HLMs for each inhibitor) using the appropriate enzyme inhibition model by nonlinear regression. At 10 microM paroxetine, sertraline, fluoxetine, or fluvoxamine, the formation of DHPBI from pimozide (10 microM) in HLMs was inhibited by an average (three HLMs) of 7%, 7.7%, 8%, and 16%, respectively, whereas this inhibition did not exceed 55% at the maximum concentrations (100 microM) of the SSRIs tested. Azithromycin [Zithromax] had negligible effect on pimozide (10 microM) N-dealkylation (19% at 100 microM azithromycin). These inhibition data were compared with ketoconazole, which was included as a positive control of CYP3A inhibition. At 0.1 microM and 0.5 microM ketoconazole, the formation of DHPBI from 10 microM pimozide was inhibited by 32% and 62%, respectively. The K(i) values (+/- SD) of ketoconazole, sertraline, fluvoxamine, azithromycin, fluoxetine, and paroxetine were 0.07 microM, 89 +/- 44 microM, 89 +/- 24 microM, 103 +/- 52 microM, 117 +/- 27 microM, and 129 +/- 33 microM, respectively. These values are least 100-fold higher than the expected plasma concentrations after the usual daily doses of the SSRIs and azithromycin, suggesting that coadministration of SSRIs and azithromycin [Zithromax] are unlikely to markedly diminish the elimination of pimozide in patients. However, in vivo predictions from in vitro data are not always perfect. In vivo, the SSRIs or azithromycin [Zithromax] may concentrate in the liver relative to plasma. In addition, the possibility that these drugs could alter pimozide disposition through effects on transport proteins or via promoter repression cannot be ruled out.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11910261&dopt=Abstract Zithromax azithromycin

pfizer.com

The comparative safety of azithromycin [Zithromax] was assessed in adult patients (> or =12 years) with community-acquired respiratory tract infections. Of 3229 patients evaluated, 1616 received azithromycin [Zithromax] 500 mg once daily for 3 days and 1613 received standard regimens of amoxycillin, amoxycillin/clavulanic acid, cefaclor, clarithromycin, or roxithromycin. A similar incidence of treatment-related adverse events occurred with azithromycin [Zithromax] (10.3%) and comparators (11.5%). Significantly fewer patients were withdrawn from azithromycin [Zithromax] than comparator treatment (0.4 versus 2.1%; P=0.0001). Most adverse events were mild/moderate in intensity and affected the gastrointestinal system. Azithromycin [Zithromax] was as well tolerated as other antibiotics commonly used for bacterial infections in adults.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11932140&dopt=Abstract Zithromax azithromycin